Field of the Invention
This invention relates to a method of carrying out washdraining, after-draining and the like in a system, preferably on board ship having at least on tank for oil or other liquid cargo, for the unloading and the draining of the oil and/or wash liquid or other liquid and for the cleaning of the tank etc, particularly from oil, sediments and other impurities as well as for the handling and refining of the more or less polluted wash liquid, and to a system for carrying out this method. Said system comprises at least one main pump, which is connected to the cargo tank through one preferably shutable main suction pipe and is adapted to substantially empty the cargo tank through a main pressure pipe, means connecting the inlet of the main pump to a flush liquid source, at least one spray nozzle or the like which is provided in the cargo tank for the cleaning thereof and is connected to the pressure pipe of the main pump or another pressure fluid source, at least one drainage pump which is preferably of the centrifugal type and is provided for wash draining and/or after-draining, and an air and gas suction off system, which is preferably connected to the main suction line trough a possible gas separation tank interconnected in the main suction line, and preferably also at least one oil or cargo liquid separation tank and means for transferring cargo and/or wash liquid from the cargo tank to the cargo liquid separation tank.